Shaped catalyst particles for hydrocarbon synthesis

ABSTRACT

The invention relates to a shaped catalyst or catalyst precursor containing a catalytically active component or a precursor therefore, the component selected from elements of Group VIII of the Periodic Table of the Elements, supported on a carrier, which catalyst or catalyst precursor is an elongated shaped particle having three protrusions each extending from and attached to a central position, wherein the central position is aligned along the longitudinal axis of the particle, the cross-section of the particle occupying the space encompassed by the outer edges of six circles around a central circle, each of the six circles touching two neighboring circles while three alternating circles are equidistant to the central circle and may be attached to the central circle, minus the space occupied by the three remaining outer circles and including the six interstitial regions. 
     The invention further relates to a process to prepare the catalyst or catalyst precursor from a shapeable dough, to the die-plate used for the preparation of an extruded catalyst or catalyst precursor, to the use of the catalysts, as well as to hydrocarbons prepared by using the catalyst. 
     The invention further relates to a process to obtain fuels and optionally base oils, by hydrogenation, hydroisomerisation and/or hydrocracking of the hydrocarbons prepared by using the catalyst.

PRIORITY CLAIM

The present application claims priority on European Patent Application02253980.3 filed 7 Jun. 2002.

FIELD OF THE INVENTION

The present invention relates to a shaped catalyst or catalystprecursor, containing a catalytically active component or a precursortherefor, the component selected from elements of Group VIII of thePeriodic Table of the Elements, supported on a carrier, the catalyst orcatalyst precursor optionally containing one or more elements orcompounds from Groups IIA, IIIB, IVB, VB, VIB, VIIB or Group VIII of thePeriodic Table of the Elements.

The invention further relates to a process to prepare the catalyst orcatalyst precursor from a shapeable dough, to the die-plate used for thepreparation of an extruded catalyst or catalyst precursor, as well as tohydrocarbons prepared by using the catalyst.

The invention further relates to a process to prepare fuels and baseoils, by hydrogenation, hydroisomerisation and/or hydrocracking of theaforementioned hydrocarbons.

BACKGROUND OF THE INVENTION

Shaped catalysts or catalyst precursors are known in the art and havebeen described, for example in European Patent EP-0,127,220.

The preparation of hydrocarbons from a gaseous mixture comprising carbonmonoxide and hydrogen by contacting the mixture with a catalyst atelevated temperature and pressure is known in the literature as theFischer-Tropsch synthesis.

Catalysts used in the Fischer-Tropsch synthesis often comprise one ormore metals from Group VIII of the Periodic Table of the Elements,optionally in combination with one or more metal oxides and/or othermetals as promoters.

It is desirable to employ a highly efficient catalyst. In terms of theFischer-Tropsch process, a highly efficient catalyst is one whichexhibits not only a high level of activity for the conversion of carbonmonoxide and hydrogen to hydrocarbons, but also a high degree ofselectivity to higher molecular hydrocarbons, in particular C₅hydrocarbons and larger, henceforth referred to as “C₅+ hydrocarbons”.Preferably, the degree of branching in the C₅+ hydrocarbons should below. It is taught in the prior art that the efficiency of a catalyst ingeneral increases as the size of the catalyst particle decreases.Further, catalysts should show a high stability, i.e. deactivationshould be very low.

The Fischer-Tropsch synthesis may be carried out using a variety ofreaction regimes, for example a fluidized bed regime or a slurry bedregime. When using a process employing a fixed bed of catalystparticles, a major consideration in the design of the process is thepressure drop through the catalyst bed. It is most desirable that thepressure drop should be as low as possible. However, it is well reportedin the art that, for a given shape of catalyst particles, as the size ofthe catalyst particles in a fixed bed is reduced, there is acorresponding increase in pressure drop through the catalyst bed. Thus,there exists a conflict in the design of fixed catalysts beds whentrying to achieve a satisfactory level of catalyst efficiency whilekeeping the pressure drop through the bed to a minimum.

In addition to the above, the catalyst particles should be sufficientlystrong to avoid undesired attrition and/or breakage. Especially in fixedbeds the bulk crush strength should be (very) high, as beds are used incommercial reactors of up to 15 meters in height. Especially at thelower end of the bed the strength of the catalyst particles plays animportant role. This is an additional complication in designing furtherimproved catalyst particles.

A still further complicating element is the manufacturing process ofcatalyst particles. There is a need for a fast, relatively inexpensiveand suitable manufacturing process which will enable the production ofcatalyst particles in large quantities. One example of such acommercially available manufacturing process is an extrusion process.

Accordingly, there exists a need for a catalyst or catalyst precursorcomprising a Group VIII element and optionally a promoter selected fromthe elements of Group IIA, Group IIIB, Group IVB, Group VB, Group VIB orGroup VIIB of the Periodic Table of the Elements which catalyst displaysa high activity and selectivity in the Fischer-Tropic synthesis process,while keeping the pressure drop in the fixed bed as low as possible anddisplaying a high crush strength and stability.

In the past a tremendous amount of work has been devoted to thedevelopment of particles, in particular catalytically active particles,for many different processes. There has also been a considerable effortto try to understand the advantages and sometimes disadvantages ofeffects of shape when deviating from conventional shapes such aspellets, rods, spheres and cylinders for use in catalytic as well asnon-catalytic duties.

Examples of further well-known shapes are rings, cloverleafs, dumbellsand C-shaped particles. Considerable efforts have been devoted to theso-called “polylobal”-shaped particles. Many commercial catalysts areavailable in TL (Trilobe) or QL (Quadrulobe) form. They serve asalternatives to the conventional cylindrical shape and often provideadvantages because of their increased surface-to-volume ratio, whichresults in a smaller effective particle size, thus providing a moreactive catalyst.

A variety of shapes and designs of catalyst particles for use in thefixed bed operation of the Fischer-Tropsch synthesis have been proposed.Thus, EP-0,428,223 discloses that the catalyst particles may be in theform of cylinders; hollow cylinders, for example cylinders having acentral hollow space which has a radius of between 0.1 and 0.4 of theradius of the cylinder; straight or rifled (twisted) trilobes; or one ofthe other forms disclosed in U.S. Pat. No. 4,028,221. Trilobe extrudatesare said to be preferred.

EP-0,218,147 discloses a helical lobed, polylobal extrudate particlehaving the outline shape of three or four strands helically wound aboutthe axis of extrusion along the length of the particle and its use as acatalyst or catalyst support, in particular as a catalyst or catalystsupport in hydrotreating operations. The helical shape of the catalystis said to reduce the pressure drop across fixed bed reactors throughwhich liquid and/or gas reactants are passed. In this way, smallercatalyst particles can be employed in a given reactor design to meet thepressure drop requirements.

In EP-0,220,933, it is described that the shape of quadrulobe-typecatalysts is important, in particular with respect to a phenomenon knownas pressure drop. From the experimental evidence provided it appearsthat asymmetric quadrulobes suffer less from pressure drop than theclosely related symmetrical quadrulobes. The asymmetrically shapedparticles are described in EP-0,220,933 by way of each pair ofprotrusions being separated by a channel which is narrower than theprotrusions to prevent entry thereinto by the protrusions of an adjacentparticle. It is taught in EP-0,220,933 that the shape of the particlesprevents them from “packing” in a bed causing the overall bulk densityof the catalyst bed to be low.

Since many of the findings in the art are conflicting and pressure dropproblems continue to be in existence, especially when surface-to-volumeratios are increased by reducing particle size, there is stillconsiderable room to search for alternative shapes of catalyticallyactive particles which would diminish or even prevent such problems.

It would be useful to find specifically shaped catalyst particles orcatalyst precursor particles that offered unexpected and sizeableadvantages compared with conventional “trilobal” catalyst particles,especially when used in mass transfer or diffusion limited reactions infixed-bed reactors, for instance as catalysts in the Fisher-Tropschprocess.

SUMMARY OF THE INVENTION

The present invention is directed to a shaped catalyst or catalystprecursor a catalytically active component or a precursor therefore, thecomponent selected from elements of Group VIII of the Periodic Table ofthe Elements, supported on a carrier, which catalyst or catalystprecursor is an elongated shaped particle comprising three protrusionseach extending from and attached to a central position, wherein thecentral position is aligned along the longitudinal axis of the particle,the cross-section of the particle occupying the space encompassed by theouter edges of six circles around a central circle, each of the sixcircles touching two neighboring circles while three alternating circlesare equidistant to the central circle and may be attached to the centralcircle, minus the space occupied by the three remaining outer circlesand including the six interstitial regions.

DETAILED DESCRIPTION OF THE INVENTION

The type of reactions which require solid catalyst particles are oftenlimited by the rate of diffusion of the reactants into the catalystparticle or by the rate of diffusion of the evolving products out of thecatalyst particle. This is especially true for liquid phases reactions.Accordingly, catalyst particles which display a high surface-to-volumeratio are advantageous.

It has been found that the catalyst particles according to the presentinvention have a larger surface-to-volume ratio than correspondingconventional “trilobal” particles of similar size and suffersubstantially less from pressure drop than such correspondingconventional “trilobal” particles, due to higher voidage. In addition, agood C₅+ selectivity and a good stability is obtained. An additionaladvantage is that the selectivity for linear (unbranched) products isincreased. Further, the particles are sufficiently strong and may easilybe made by extrusion.

The shaped catalyst particles may be formed of any suitable materialprovided it is capable of being processed in such a way that theintended shape is obtained. Methods of preparing such shapes includepressing, extruding or otherwise forcing a granular or powdered catalystor catalyst precursor material into various shapes under certainconditions, which will ensure that the particle retains the resultingshape, both during reaction as well as during regeneration.

The catalysts of the present invention, especially for use in theFischer-Tropsch process, comprise, as the catalytically activecomponent; a metal from Group VIII of the Periodic Table of theElements. Particular catalytically active metals include ruthenium,iron, cobalt and nickel, more preferably cobalt. Combinations of two ormore components are also possible. Preferably, a Fischer-Tropschcatalyst is used; which yields substantial quantities of paraffins, morepreferably substantially unbranched paraffins. A most suitable catalystcomposition for this purpose includes a cobalt-containingFischer-Tropsch catalyst. Such catalysts are described in theliterature, see e.g. AU 698392 and WO 99/34917. Preferredhydrocarbonaceous feeds for the preparation of synthesis gas are naturalgas or associated gas. As these feedstocks usually result in synthesisgas having H₂/CO ratio's of close to 2, cobalt is a very goodFischer-Tropsch catalyst as the user ratio for this type of catalysts isalso about 2.

The catalytically active metal is preferably sup-ported on a porouscarrier. The porous carrier may be selected from any of the suitablerefractory metal oxides or silicates or combinations thereof known inthe art. Particular examples of preferred porous carriers includesilica, alumina, titania, zirconia, ceria, gallia and mixtures thereof,especially silica, alumina and titania, especially TiO₂.

The amount of catalytically active metal on the carrier for optimumperformance is preferably in the range of from 3 to 300 pbw per 100 pbwof carrier material, more preferably from 10 to 80 pbw, especially from20 to 60 pbw.

If desired, the catalyst may also comprise one or more metals or metaloxides as promoters. Suitable metal oxide promoters may be selected fromGroups IIA, IIIB, IVB, VB, VIB or Group VIIB of the Periodic Table ofthe Elements, or the actinides and lanthanides. In particular, oxides ofmagnesium, calcium, strontium, barium, scandium, yttrium, lanthanum,titanium, zirconium, hafnium, cerium, thorium, uranium, vanadium,chromium and manganese are very suitable promoters. Particularlypreferred metal oxide promoters for the catalyst used to prepare heavyparaffins are manganese, vanadium and zirconium oxide. Suitable metalpromoters may be selected from Groups VIIB or VIII of the Periodic Tableof the Elements. Rhenium, silver and Group VIII noble metals areparticularly suitable, with platinum and palladium being especiallypreferred. The amount of promoter present in the catalyst is suitably inthe range of from 0.01 to 100 pbw, preferably 0.1 to 40, more preferably1 to 20 pbw, per 100 pbw of carrier. The most preferred promoters areselected from vanadium, manganese, rhenium, zirconium and platinum inview of their ability to produce long chain n-paraffins.

The catalytically active metal and the promoter, if present, may bedeposited on the carrier material by any suitable treatment, such asimpregnation, mixing/kneading and mixing/extrusion. After deposition ofthe metal and, if appropriate, the promoter on the carrier material, theloaded carrier is typically subjected to calcination. The effect of thecalcination treatment is to remove crystal water, to decompose organiccompounds and to convert inorganic compounds to their respective oxides.After calcination, the resulting catalyst may be activated by contactingthe catalyst with hydrogen or a hydrogen-containing gas, typically attemperatures of about 200 to 350° C. Other processes for the preparationof Fischer-Tropsch catalysts comprise kneading/mulling, followed byextrusion, drying/calcination and activation.

The suitable material for the shaped catalyst particles should beprocessed in such a way that the intended shape is obtained. One exampleof a processing method is an extrusion process, wherein a shapeabledough, preferably comprising one or more sources for one or more of thecatalytically active elements, and optionally one or more sources forone or more of the promoters and the finely divided refractory oxide orrefractory oxide precursor is mulled together with a suitable solvent.The mulled mixture is then extruded through an orifice in a die-plate.The resulting extrudates are dried. If necessary, (additional) catalyticelement sources and/or promoters may be applied to the extrudates byimpregnation. Other processes which may be used are palletizing andpressure molding.

The solvent for inclusion in the mixture may be any of the suitablesolvents known in the art. Examples of suitable solvents include water;alcohols, such as methanol, ethanol and propanol; ketones, such asacetone; aldehydes, such as propanal; and aromatic solvents, such astoluene. A most convenient and preferred solvent is water, optionally incombination with methanol.

The use of specific die-plates enables the formation of the intendedshape of the catalyst particles. Die-plates are known in the art and maybe made from metal or polymer material, especially a thermoplasticmaterial.

Preferred catalyst particles according to the present invention have across-section in which the three alternating circles (forming part ofthe outer circles) have diameters in the range of between 0.74 and 1.3times the diameter of the central circle, preferably between 0.87 and1.15 times the diameter of the central circle.

More preferred catalyst particles according to the present invention arethose having a cross-section in which the three alternating circles havethe same diameter as the central circle. Suitably the distance betweenthe three alternating circles and the central circle is the same. Thisdistance is preferably less than half the diameter of the centralcircle, more preferably less than a quarter of the diameter of thecentral circle, with most preference given to particles having across-section in which the three alternating circles are attached to thecentral circle. Preferably the three alternating circles do not overlapwith the central circle. In case of any overlap, the overlap of eachalternating circle and the central circle will be less than 5% of thearea of the central circle, preferably less than 2%, more preferablyless than 1%.

In FIG. 1 a cross-sectional view of the most preferred particlesaccording to the invention has been depicted. The surface of thecross-sectional shape is (indicated by the solid line). It will be clearfrom Fig. (depicting the cross-section of the preferred particles) thatin the concept of six circles of equal size aligned around a centralcircle of the same size each outer circle borders its two neighborcircles and the central circle while subtraction of three alternatingouter circles (indicated by the dotted line) provides the remainingcross-section, built up from four circles (the central circle and thethree remaining alternating outer circles) together with the six areasformed by the inclusions of the central circle and six times twoadjacent outer circles. These areas are referred to as “interstitialareas”. The three remaining alternating outer circles are equidistant tothe central circle. The term “equidistant” as used herein refers to thecircumstance that the distance between the center of the central circleto the center of one of the outer circles is equal to the distancebetween the center of the central circle to the centre of either one ofthe other remaining outer circles. For the purpose of this specificationthe term “equidistant” may comprise deviations up to 20% of thedistance, preferably up to 10%, more preferably up to 5%. In the mostpreferred embodiment there is no deviation. The circumference of thepreferred shaped particles according to the present invention is suchthat it does not contain sharp corners, which can also be expressed asthe derivative of the cross-section being continuous. The diameter ofthe particles (the most preferred particles in accordance with thepresent invention) is defined as the distance between the tangent linethat touches two protrusions and a line parallel to this tangent linethat touches the third protrusion. It is indicated as d nom in FIG. 1.In the case that the three alternating circles have one or two differentdiameters, d nom is the sum of the three measured diameters divided bythree.

The three protrusions and the central position together form thecross-section of the catalyst or catalyst precursor. The main part ofeach protrusion is formed by one of the (remaining) alternating circles.The main part of the central protrusion is formed by the central circle.The interstitial areas are divided between the central position and theprotrusion by a line perpendicular to the line connecting the centerpoint of the central circle and the center part of the alternatingcircle. The perpendicular line (dotted line) crosses the connecting line(solid line) at a point exactly in the middle between the two centerpoints (see FIG. 2).

It will be clear that minor deviations from the shape as defined areconsidered to be within the scope of the present invention. In the casewhere the catalyst or catalyst precursor of the present invention isprepared by an extrusion process, die-plates are used. It is known tothose skilled in the art to manufacture die-plates having one or moreholes in the desired shape of the particles, in this case according tothe present invention. Tolerances may be expected in practice whenproducing such die-plates. In this respect it is observed that thepressure release immediately after extrusion may result in deformationof the extrudates. Usually the minor deviations are within 10%,preferably within 5%, more preferably within 2% of d nom with respect tothe ideal shape as defined in the present invention.

After a typical process of preparation of the catalyst or catalystprecursor particles of the invention, between 10% and 100% of the numberof particles produced preferably have a nominal diameter with adeviation of less than 5% of the shape as defined in the presentinvention. Preferably, at least 50% of the catalyst particles have anominal diameter with a deviation of less than 5% of the shape asdefined in the present invention.

It is possible to produce catalyst particles according to the presentinvention which also contain one or more holes along the length of theparticles. For instance, the particles can contain one or more holes inthe area formed by the central cylinder (the central circle in thecross-section given in FIG. 1) and/or one or more holes in one or moreof the alternating cylinders (the alternating circles in thecross-section given in FIG. 1). The presence of one or a number of holescauses an increase of the surface to volume ratio which in principleallows exposure of more catalytic sites and, in any case, more exposureto incoming charges which may work advantageously from a catalytic pointof view. Since it becomes increasingly difficult to produce hollowparticles as their size becomes smaller it is preferred to use porousparticles without holes when smaller sizes are desired for certainpurposes.

It has been found that the voidage of the catalyst particles accordingto the present invention is well above 50% (voidage being defined as thevolume fraction of the open space present in a bed of particles outsidethe particles present, i.e. the volume of the pores inside the particlesare not included in the voidage). The particles used in the experimentto be described hereinafter had a voidage of typically 58% which issubstantially above that of the comparative “trilobal” particle, thevoidage of which amounted to just over 43%. The voidage of a bed ofcatalyst particles according to the invention is suitably between 45 and80%, preferably between 50 and 70%, more preferably between 55 and 65%.

The catalyst particles according to the present invention may bedescribed as having a length/diameter ratio (L/D) of at least 1. Theparticles according to the present invention may have a L/D in the rangebetween 1 and 25. Preferably, the particles according to the presentinvention have a L/D in the range between 1.5 and 20, more preferably inthe range between 2 and 10. For example, the particles used in theexperiment to be described hereinafter had a L/D of about 2.5.

The length of the particles in accordance with the present invention issuitably in the range between 1 and 25 mm, preferably in the rangebetween 2 and 20 mm, depending on the type of application envisaged.

The catalytic conversion process may be performed under conventionalsynthesis conditions known in the art. Typically, the catalyticconversion may be effected at a temperature in the range of from 150° C.to 300° C., preferably from 180° C. to 260° C. Typical total pressuresfor the catalytic conversion process are in the range of from 1 bar to200 bar absolute, more preferably from 10 bar to 70 bar absolute. In thecatalytic conversion process especially more than 75 wt % of C₅+,preferably more than 85 wt % C₅+ hydrocarbons are formed. In a typicalconversion process using a catalyst according to the present invention,the amount of products comprising one or more tertiary substitutedcarbon atoms (henceforth referred to as “branched” products) may be atleast 20% less compared to a conversion process with similar reactionconditions, where a conventional trilobal catalyst is used. Depending onthe catalyst and the conversion conditions, the amount of heavy wax(C₂₀+) may be up to 60 wt %, sometimes up to 70 wt %, and sometimes evenup to 85 wt %. Preferably a cobalt catalyst is used, a low H₂/CO ratiois used (especially 1.7, or even lower) and a low temperature is used(190-230° C.). To avoid any coke formation, it is preferred to use anH₂/CO ratio of at least 0.3. It is especially preferred to carry out theFischer-Tropsch reaction under such conditions that the SF-alpha value,for the obtained products having at least 20 carbon atoms, is at least0.925, preferably at least 0.935, more preferably at least 0.945, evenmore preferably at least 0.955. Preferably the Fischer-Tropschhydrocarbons stream comprises at least 35 wt % C₃₀+, preferably 40 wt %,more preferably 50 wt %.

The Fischer-Tropsch process may be a slurry FT process, especially anebulated bed process or a fixed bed FT process, especially amultitubular fixed bed process. It has been found that the bedscontaining particles according to the invention have—in a randompacking—a much higher voidage than beds containing the correspondingconventional trilobes when packed using the well known “sock loading”technique. The voidage obtained when using the conventional trilobalshape amounts up to about 45% whereas use of the particles according tothe present invention produces a voidage of at least 55% which makessuch particles attractive for low pressure drop applications, forinstance the Fischer-Tropsch synthesis process.

The catalyst particles described herein can also be formed as helicallobed particles. The term helical lobed particles as used herein refersto an elongated shaped particle comprising three protrusions eachextending from and attached to a central position, the central positionbeing aligned along a longitudinal axis, the particle having across-section occupying the space encompassed by the outer edges of sixcircles around a central circle, each of the six circles bordering twoneighboring circles while three alternating circles are equidistant tothe central circle and may be attached to the central circle, minus thespace occupied by the three remaining outer circles and including thesix interstitial regions, which protrusions extend along and arehelically wound about the longitudinal axis of the particle.

By employing helical lobed particles, a larger diameter helical lobedcatalyst particle may be employed to achieve a given selectivity than isnecessary when employing straight lobed particles, resulting in agreater reduction in pressure drop across the catalyst bed than expectedfrom the prior art. Alternatively, for a given design of fixed bed witha predetermined pressure drop, by employing the helical lobed particlesin the Fischer-Tropsch process a substantially higher selectivity may beachieved than with the appropriate straight lobed particles necessary tomeet the pressure drop requirements.

The invention will now be illustrated by means of the followingnon-limiting examples.

Experiments were carried out to monitor the Fischer-Tropsch processusing catalyst particles made up of trilobe-shaped extrudates(comparative example) and using catalyst particles according to theinvention (working examples).

Example I Preparation of Trilobe-Shaped Catalyst Particles (Comparative)

Trilobe-shaped catalyst particles were prepared as follows. A mixturewas prepared containing 143 g commercially available titania powder (P25ex. Degussa), 66 g commercially available Co(OH)₂ powder, 10.3 gMn(Ac)₂.4H₂O and 38 g water. The mixture was kneaded for 15 minutes. Themixture was shaped using a Bonnot extruder. The resulting extrudateswere dried and calcined. The resulting extrudates contained 20 wt % Coand 1 wt % Mn. The resulting catalyst particles had a trilobal shapehaving a nominal diameter of 1.7 mm (Catalyst A).

Example II Preparation of Catalyst Particles According to the PresentInvention

A mixture was prepared containing 143 g commercially available titaniapowder (P25 ex. Degussa), 66 g commercially available Co(OH)₂ powder,10.3 g Mn(Ac)₂.4H₂O and 38 g water. The mixture was kneaded for 15minutes. The mixture was shaped using a Bonnot extruder equipped with anappropriate dieplate to obtain the desired shape as desired in claim 1.The resulting extrudates were dried and calcined. The resulting catalystparticles contained 20 wt % Co and 1 wt % Mn and had shapes as definedin claim 1 with nominal diameters of 1.7 mm (Catalyst B), 1.5 mm(Catalyst C), 1.3 mm (Catalyst D) and 1.0 mm (Catalyst E) respectively.

Example III

Catalysts A and B were tested in a process for the preparation ofhydrocarbons. Micro-flow reactors containing 10 ml of catalystextrudates A and B, respectively, in the form of a fixed bed of catalystparticles, were heated to a temperature of 260° C., and pressurised witha continuous flow of nitrogen gas to a pressure of 2 bar abs. Thecatalysts were reduced in-situ for 24 hours with a mixture of nitrogenand hydrogen gas. During reduction the relative amount of hydrogen inthe mixture was gradually increased from 0% to 100%. The waterconcentration in the off-gas was kept below 3000 ppmv.

Following reduction, the pressure was increased to 32 bara (STY 140) or57 bara (STY 180). The reaction was carried out with a mixture ofhydrogen and carbon monoxide. The space time yield (STY), expressed asgrams hydrocarbon product per liter catalyst particles (including thevoids between the particles) per hour, the C₅+ selectivity, expressed asa weight percentage of the total hydrocarbon product, and the ratio ofunsaturated product versus saturated product for products having between2 and 4 hydrocarbons were determined for each experiment after 50 hoursof operation. The results are set out in Table I.

TABLE I Relative C₅+ Relative CO₂ Relative STY selectivity sel g/lcat/h(%) (%) Catalyst B 140 102.0 64.0 180 104.0 55.0

In Table I, the results regarding C₅+ selectivity resulting from the useof catalyst B are expressed relative to the results obtained from theuse of catalyst A, i.e. the C₅+ selectivity of catalyst A is taken to be100%.

From the results it is clear that catalyst B gives a better performancethan catalyst A with respect to C₅+ selectivity in the Fischer-Tropschprocess. The performance of catalyst B is better even though the amountof active material per volume reactor is smaller for catalyst B than forcatalyst A, due to the higher voidage. Thus, the specific shape of thecatalyst B particles enables a better use of the expensive catalystmaterial.

Example IV

Catalysts A, C, D and E were tested in a process for the preparation ofhydrocarbons. Micro-flow reactors containing 10 ml of catalystextrudates A, C, D and E, respectively, in the form of a fixed bed ofcatalyst particles, were heated to a temperature of 260° C., andpressurized with a continuous flow of nitrogen gas to a pressure of 2bar abs. The catalysts were reduced in-situ for 24 hours with a mixtureof nitrogen and hydrogen gas. During reduction, the relative amount ofhydrogen in the mixture was gradually increased from 0% to 100%. Thewater concentration in the off-gas was kept below 3000 ppmv.

Following reductions the pressure was increased to 26 bar abs. Thereaction was carried out with a mixture of hydrogen and carbon monoxide.The reaction temperature is expressed as the weighted average bedtemperature (WABT) in ° C. The space time yield (STY), expressed asgrams hydrocarbon product per liter catalyst particles (including thevoids between the particles) per hour, the C₅+ selectivity, expressed asa weight percentage of the total hydrocarbon product, and the ratio ofunsaturated product versus saturated product for products having between2 and 4 hydrocarbons were determined for each experiment after 50 hoursof operation. The results are set out in Table II.

TABLE II Catalyst C Catalyst D Catalyst E Inert, % 0 50 0 50 0 50Relative STY 200 132 200 132 200 132 Relative C₅ + sel, 103 103 104 103104 103 % w/Cl+ Relative C₁₁-C₁₄ 184 238 183 320 184 315 olefinicity, %w

In Table II, the results from the use of catalysts C, D or E areexpressed relative to the results obtained from the use of catalyst A.

From the results in Table II it is clear that catalysts C, D and E givea better performance than catalyst A in the Fischer-Tropsch process. Theperformance of catalysts C, D and E is better even though the amount ofactive material per volume reactor is smaller for catalysts C, D and Ethan for catalyst A, due to the higher voidage. Thus, the specific shapeof catalyst C, D and E particles enables a better use of the expensivecatalyst material.

1. A shaped catalyst or catalyst precursor containing a catalyticallyactive component or a precursor thereof, wherein the component isselected from the group consisting of ruthenium, iron, cobalt andnickel, supported on a cater, which catalyst or catalyst precursor is anelongated shaped particle comprising three protrusions each extendingfrom and attached to a central position, wherein the central position isaligned along the longitudinal axis of the particle, the cross-sectionof the particle occupying the space encompassed by the outer edges ofsix circles around a central circle, each of the six circles touchingtwo neighboring circles while three alternating circles are equidistantto the central circle and may be attached to the central circle, minusthe space occupied by the three remaining outer circles and includingthe six interstitial regions, the shaped catalyst or catalyst precursorhaving a cross-section in which the three remaining alternating circleshave diameters in the range between 0.74 and 1.3 times the diameter ofthe central circle, the overlap of each alternating circle and thecentral circle being less than 5% of the area of the central circle. 2.The shaped catalyst or catalyst precursor of claim 1, wherein theprotrusions are helically wound around the longitudinal axis of theparticle.
 3. The shaped catalyst or catalyst precursor of claim 1,having a nominal diameter D in the range between 0.5 and 5 mm.
 4. Theshaped catalyst or catalyst precursor of claim 1, wherein thecatalytically active component or a precursor therefore is cobalt. 5.The shaped catalyst or catalyst precursor of claim 1, further containingan element or compound selected from the group consisting of Group IIA,IIIB, IVB, VB, VIB and, VIIB of the Periodic Table of the Elements. 6.The shaped catalyst or catalyst precursor of claim 1, wherein the cateris a refractory oxide.
 7. The shaped particle of claim 6, wherein therefractory oxide is selected from the group consisting of silica,alumina and titania.
 8. The shaped catalyst or catalyst precursor ofclaim 1, having a cross-section in which the three remaining alternatingcircles have diameters in the range between 0.87 and 1.15 times thediameter of the central circle.
 9. The shaped particle of claim 8,having a cross section in which the three remaining alternating circleshave the same diameter as the central circle.
 10. The shaped particle ofclaim 8, wherein the three alternating circles are attached to thecentral circle.
 11. The shaped catalyst or catalyst precursor of claim1, having a length to diameter ratio (mm/mm) of between 1 and 25 and alength in the range between 1 and 25 mm.
 12. The shaped catalyst orcatalyst precursor of claim 11, having a length to diameter ratiobetween 2 and 10 and a length between 2 mm and 20 mm.
 13. A process forthe preparation of a catalyst or catalyst precursor containing acatalytically active component or a precursor therefore, the componentselected from the group consisting of ruthenium, iron, cobalt andnickel, supported on a carrier, which catalyst or catalyst precursor isan elongated shaped particle comprising three protrusions each extendingfrom and attached to a central position, wherein the central position isaligned along the longitudinal axis of the particle, the cross-sectionof the particle occupying the space encompassed by the outer edges ofsix circles around a central circle, each of the six circles touchingtwo neighboring circles while three alternating circles are equidistantto the central circle and may be attached to the central circle, minusthe space occupied by the three remaining outer circles and includingthe six interstitial regions, the shaped catalyst or catalyst precursorhaving a cross-section in which the three remaining alternating circleshave diameters in the range between 0.74 and 1.3 times the diameter ofthe central circle, the overlap of each alternating circle and thecentral circle being less than 5% of the area of the central circle,comprising: pressing, extruding or forcing a granular or powderedcatalyst or catalyst precursor material into various shapes undercertain conditions, which will ensure that the particle retains theresulting shape, both during reaction as well as regeneration.
 14. Adie-plate designed for use in the preparation of a catalyst or catalystprecursor by extrusion, wherein the die-plate comprises one or moreorifices in the shape of the cross-section of carrier particlescomprising an elongated shaped particle comprising three protrusionseach extending from and attached to a central position, wherein thecentral position is aligned along the longitudinal axis of the particle,the cross-section of the particle occupying the space encompassed by theouter edges of six circles around a central circle, each of the sixcircles touching two neighboring circles while three alternating circlesare equidistant to the central circle and may be attached to the centralcircle, minus the space occupied by the three remaining outer circlesand including the six interstitial regions, the shaped catalyst orcatalyst precursor having a cross-section in which the three remainingalternating circles have diameters in the range between 0.74 and 1.3times the diameter of the central circle, the overlap of eachalternating circle and the central circle being less than 5% of the areaof the central circle.
 15. A process for the preparation of hydrocarbonscomprising contacting a mixture of carbon monoxide and hydrogen with acatalyst comprising a catalytically active component or a precursortherefore, wherein the component is selected from the group consistingof ruthenium, iron, cobalt and nickel, supported on a carrier, whichcatalyst or catalyst precursor is an elongated shaped particlecomprising three protrusions each extending from and attached to acentral position, wherein the central position is aligned along thelongitudinal axis of the particle, the cross-section of the particleoccupying the space encompassed by the outer edges of six circles arounda central circle, each of the six circles touching two neighboringcircles while three alternating circles are equidistant to the centralcircle and may be attached to the central circle, minus the spaceoccupied by the three remaining outer circles and including the sixinterstitial regions, the shaped catalyst or catalyst precursor having across-section in which the three remaining alternating circles havediameters in the range between 0.74 and 1.3 times the diameter of thecentral circle, the overlap of each alternating circle and the centralcircle being less than 5% of the area of the central circle, and thecatalyst is optionally activated by contacting the catalyst precursorwith hydrogen or a hydrogen containing gas.
 16. A process comprisingpreparing fuels and optionally base oils from hydrocarbons produced bythe process for the preparation of hydrocarbons comprising contacting amixture of carbon monoxide and hydrogen with a catalyst comprising acatalytically active component or a precursor therefore, wherein thecomponent is selected from the group consisting of ruthenium, iron,cobalt and nickel, supported on a cater, which catalyst or catalystprecursor is an elongated shaped particle comprising three protrusionseach extending from and attached to a central position, wherein thecentral position is aligned along the longitudinal axis of the particle,the cross-section of the particle occupying the space encompassed by theouter edges of six circles around a central circle, each of the sixcircles touching two neighboring circles while three alternating circlesare equidistant to the central circle and may be attached to the centralcircle, minus the space occupied by the three remaining outer circlesand including the six interstitial regions, the shaped catalyst orcatalyst precursor having a cross-section in which the three remainingalternating circles have diameters in the range between 0.74 and 1.3times the diameter of the central circle, the overlap of eachalternating circle and the central circle being less than 5% of the areaof the central circle, and the catalyst is optionally activated bycontacting the catalyst precursor with hydrogen or a hydrogen containinggas, by hydrogenation, hydroisomerisation and/or hydrocracking. 17.Fuels and base oils prepared by a process according to claim 16.